. . "http://en.wikipedia.org/wiki/Cross_section_(physics)"^^ . "\"Cross-section\" is used to express the likelihood of interaction between particles. For a specified target particle and for a specified reaction or process produced by incident charged or uncharged particles of specified type and energy, it is the mean number of such reactions or processes divided by the incident-particle fluence." . "Cross-section"@en . . . . . . "http://www.iso.org/iso/catalogue_detail?csnumber=31895"^^ . . . . "\u03C3" . . . . . . . . . . . .